1. __ are north-south lines that form half circles between the North Pole the South Pole

The question is asking about the lines that form half circles between the North Pole and the South Pole on the Earth's surface. These lines are known as meridians or meridian lines. They are imaginary lines that run from the North Pole to the South Pole, passing through the Earth's surface. These lines are used in navigation and geography to determine longitude and latitude. The meridian that passes through Greenwich, England, is known as the Prime Meridian, and it is designated as 0° longitude. All other meridians are measured in degrees east or west of the Prime Meridian. The meridians are perpendicular to the equator, which is an imaginary line that circles the Earth horizontally, dividing it into the Northern and Southern Hemispheres.